/*
 *
 * esda/utils/MD5.cxx --
 *
 * Copyright (C) Olivier Le Floch
 *
 * See the file LICENSE for information on usage and redistribution of
 * this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * This code originally comes from http://www.fourmilab.ch/md5/
 * See http://en.wikipedia.org/wiki/MD5 for some background information
 *
 */

#include <esda/utils/MD5.H>
#include <esda/utils/ByteOrder.H>

#include <iomanip>
#include <iostream>
#include <sstream>
#include <stdexcept>

namespace esda {

	/*
	 * This code implements the MD5 message-digest algorithm.
	 * The algorithm is due to Ron Rivest.	This code was
	 * written by Colin Plumb in 1993, no copyright is claimed.
	 * This code is in the public domain; do with it what you wish.
	 *
	 * Equivalent code is available from RSA Data Security, Inc.
	 * This code has been tested against that, and is equivalent,
	 * except that you don't need to include two pages of legalese
	 * with every copy.
	 *
	 * To compute the message digest of a chunk of bytes, declare an
	 * MD5Context structure, pass it to MD5Init, call MD5Update as
	 * needed on buffers full of bytes, and then call MD5Final, which
	 * will fill a supplied 16-byte array with the digest.
	 */

	/* Brutally hacked by John Walker back from ANSI C to K&R (no
	prototypes) to maintain the tradition that Netfone will compile
	with Sun's original "cc". */

	/* Converted to C++ by Olivier Le Floch */

	// -------------------------------------------------------------------------

	static inline void
	byteReverse(unsigned char *buf, unsigned int longs) {
		if (ByteOrder::isLittleEndian()) return ;
		do {
	 uint32_t t = (uint32_t) ((unsigned) buf[3] << 8 | buf[2]) << 16 | ((unsigned) buf[1] << 8 | buf[0]) ;
	 *(uint32_t *)buf = t ;
	 buf += 4 ;
		} while (--longs) ;
	}

	// -------------------------------------------------------------------------
	// The four core functions

#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))

	// This is the central step in the MD5 algorithm.
	
#define MD5STEP(f, w, x, y, z, data, s)						\
	( w += f(x, y, z) + data,	w = w<<s | w>>(32-s),	w += x )

	// The core of the MD5 algorithm, this alters an existing MD5 hash
	// to reflect the addition of 16 longwords of new data.	MD5Update
	// blocks the data and converts bytes into longwords for this
	// routine.

	void
	MD5::transform(uint32_t *buffer, uint32_t *input) {
		register uint32_t a, b, c, d;

		a = buffer[0];
		b = buffer[1];
		c = buffer[2];
		d = buffer[3];

		MD5STEP(F1, a, b, c, d, input[0] + 0xd76aa478, 7);
		MD5STEP(F1, d, a, b, c, input[1] + 0xe8c7b756, 12);
		MD5STEP(F1, c, d, a, b, input[2] + 0x242070db, 17);
		MD5STEP(F1, b, c, d, a, input[3] + 0xc1bdceee, 22);
		MD5STEP(F1, a, b, c, d, input[4] + 0xf57c0faf, 7);
		MD5STEP(F1, d, a, b, c, input[5] + 0x4787c62a, 12);
		MD5STEP(F1, c, d, a, b, input[6] + 0xa8304613, 17);
		MD5STEP(F1, b, c, d, a, input[7] + 0xfd469501, 22);
		MD5STEP(F1, a, b, c, d, input[8] + 0x698098d8, 7);
		MD5STEP(F1, d, a, b, c, input[9] + 0x8b44f7af, 12);
		MD5STEP(F1, c, d, a, b, input[10] + 0xffff5bb1, 17);
		MD5STEP(F1, b, c, d, a, input[11] + 0x895cd7be, 22);
		MD5STEP(F1, a, b, c, d, input[12] + 0x6b901122, 7);
		MD5STEP(F1, d, a, b, c, input[13] + 0xfd987193, 12);
		MD5STEP(F1, c, d, a, b, input[14] + 0xa679438e, 17);
		MD5STEP(F1, b, c, d, a, input[15] + 0x49b40821, 22);

		MD5STEP(F2, a, b, c, d, input[1] + 0xf61e2562, 5);
		MD5STEP(F2, d, a, b, c, input[6] + 0xc040b340, 9);
		MD5STEP(F2, c, d, a, b, input[11] + 0x265e5a51, 14);
		MD5STEP(F2, b, c, d, a, input[0] + 0xe9b6c7aa, 20);
		MD5STEP(F2, a, b, c, d, input[5] + 0xd62f105d, 5);
		MD5STEP(F2, d, a, b, c, input[10] + 0x02441453, 9);
		MD5STEP(F2, c, d, a, b, input[15] + 0xd8a1e681, 14);
		MD5STEP(F2, b, c, d, a, input[4] + 0xe7d3fbc8, 20);
		MD5STEP(F2, a, b, c, d, input[9] + 0x21e1cde6, 5);
		MD5STEP(F2, d, a, b, c, input[14] + 0xc33707d6, 9);
		MD5STEP(F2, c, d, a, b, input[3] + 0xf4d50d87, 14);
		MD5STEP(F2, b, c, d, a, input[8] + 0x455a14ed, 20);
		MD5STEP(F2, a, b, c, d, input[13] + 0xa9e3e905, 5);
		MD5STEP(F2, d, a, b, c, input[2] + 0xfcefa3f8, 9);
		MD5STEP(F2, c, d, a, b, input[7] + 0x676f02d9, 14);
		MD5STEP(F2, b, c, d, a, input[12] + 0x8d2a4c8a, 20);

		MD5STEP(F3, a, b, c, d, input[5] + 0xfffa3942, 4);
		MD5STEP(F3, d, a, b, c, input[8] + 0x8771f681, 11);
		MD5STEP(F3, c, d, a, b, input[11] + 0x6d9d6122, 16);
		MD5STEP(F3, b, c, d, a, input[14] + 0xfde5380c, 23);
		MD5STEP(F3, a, b, c, d, input[1] + 0xa4beea44, 4);
		MD5STEP(F3, d, a, b, c, input[4] + 0x4bdecfa9, 11);
		MD5STEP(F3, c, d, a, b, input[7] + 0xf6bb4b60, 16);
		MD5STEP(F3, b, c, d, a, input[10] + 0xbebfbc70, 23);
		MD5STEP(F3, a, b, c, d, input[13] + 0x289b7ec6, 4);
		MD5STEP(F3, d, a, b, c, input[0] + 0xeaa127fa, 11);
		MD5STEP(F3, c, d, a, b, input[3] + 0xd4ef3085, 16);
		MD5STEP(F3, b, c, d, a, input[6] + 0x04881d05, 23);
		MD5STEP(F3, a, b, c, d, input[9] + 0xd9d4d039, 4);
		MD5STEP(F3, d, a, b, c, input[12] + 0xe6db99e5, 11);
		MD5STEP(F3, c, d, a, b, input[15] + 0x1fa27cf8, 16);
		MD5STEP(F3, b, c, d, a, input[2] + 0xc4ac5665, 23);

		MD5STEP(F4, a, b, c, d, input[0] + 0xf4292244, 6);
		MD5STEP(F4, d, a, b, c, input[7] + 0x432aff97, 10);
		MD5STEP(F4, c, d, a, b, input[14] + 0xab9423a7, 15);
		MD5STEP(F4, b, c, d, a, input[5] + 0xfc93a039, 21);
		MD5STEP(F4, a, b, c, d, input[12] + 0x655b59c3, 6);
		MD5STEP(F4, d, a, b, c, input[3] + 0x8f0ccc92, 10);
		MD5STEP(F4, c, d, a, b, input[10] + 0xffeff47d, 15);
		MD5STEP(F4, b, c, d, a, input[1] + 0x85845dd1, 21);
		MD5STEP(F4, a, b, c, d, input[8] + 0x6fa87e4f, 6);
		MD5STEP(F4, d, a, b, c, input[15] + 0xfe2ce6e0, 10);
		MD5STEP(F4, c, d, a, b, input[6] + 0xa3014314, 15);
		MD5STEP(F4, b, c, d, a, input[13] + 0x4e0811a1, 21);
		MD5STEP(F4, a, b, c, d, input[4] + 0xf7537e82, 6);
		MD5STEP(F4, d, a, b, c, input[11] + 0xbd3af235, 10);
		MD5STEP(F4, c, d, a, b, input[2] + 0x2ad7d2bb, 15);
		MD5STEP(F4, b, c, d, a, input[9] + 0xeb86d391, 21);

		buffer[0] += a;
		buffer[1] += b;
		buffer[2] += c;
		buffer[3] += d;
	}

	// -------------------------------------------------------------------------

	// Start MD5 accumulation. Set bit count to 0 and buffer to
	// mysterious initialization constants.

	MD5::MD5(void) {
		clear() ;
	}

	void
	MD5::clear(void) {
		buf[0] = 0x67452301 ;
		buf[1] = 0xefcdab89 ;
		buf[2] = 0x98badcfe ;
		buf[3] = 0x10325476 ;
		bits[0] = bits[1] = 0 ;
		for (int i=0; i<64; ++i) in[i] = 0 ;
	}

	// Update context to reflect the concatenation of another buffer
	// full of bytes.

	void
	MD5::eat(const unsigned char *data, unsigned int size) {
		// Update bitcount
		uint32_t t = bits[0];
		if ((bits[0] = t + ((uint32_t) size << 3)) < t)
	bits[1]++; 	/* Carry from low to high */
		bits[1] += size >> 29;

		t = (t >> 3) & 0x3f;	/* Bytes already in shsInfo->data */

		// Handle any leading odd-sized chunks

		if (t) {
	unsigned char *p = (unsigned char *) in + t;

	t = 64 - t;
	if (size < t) {
			memcpy(p, data, size);
			return;
	}
	memcpy(p, data, t);
	byteReverse(in, 16);
	transform((uint32_t*)buf, (uint32_t *) in);
	data += t;
	size -= t;
		}
		/* Process data in 64-byte chunks */

		while (size >= 64) {
	memcpy(in, data, 64);
	byteReverse(in, 16);
	transform((uint32_t*)buf, (uint32_t *) in);
	data += 64;
	size -= 64;
		}

		/* Handle any remaining bytes of data. */

		memcpy(in, data, size);
	}

	// -------------------------------------------------------------------------

	// Final wrapup - pad to 64-byte boundary with the bit pattern 1 0*
	// (64-bit count of bits processed, MSB-first)

	void
	MD5::digest(bytearray digest) {
		// Compute number of bytes mod 64
		unsigned count = (bits[0] >> 3) & 0x3F;

		// Set the first char of padding to 0x80.	This is safe since
		// there is always at least one byte free
		unsigned char *p = in + count;
		*p++ = 0x80;

		// Bytes of padding needed to make 64 bytes
		count = 64 - 1 - count;

		// Pad out to 56 mod 64
		if (count < 8) {
	 // Two lots of padding:	Pad the first block to 64 bytes
	 memset(p, 0, count);
	 byteReverse(in, 16);
	 transform(buf, (uint32_t *) in);
	 // Now fill the next block with 56 bytes
	 memset(in, 0, 56);
		} else {
	 // Pad block to 56 bytes
	 memset(p, 0, count - 8);
		}
		byteReverse(in, 14);

		// Append length in bits and transform
		((uint32_t *) in)[14] = bits[0];
		((uint32_t *) in)[15] = bits[1];

		transform(buf, (uint32_t *) in);
		byteReverse((unsigned char *) buf, 4);

		memcpy(digest, buf, 16);

		clear() ; // In case it's sensitive
	}

	string
	MD5::digest(void) {
		bytearray d ;
		digest(d) ;

		stringstream result ;
		for (int i=0; i<16; ++i) 
	 result << hex << setfill('0') << setw(2) << (int)d[i] ;
		// cerr << "MD5: " << result.str() << endl ;
		return result.str() ;
	}

}
